Some compositions comprise an internal phase dispersed in a continuous phase, namely in particular, emulsions and foams.
An emulsion is a mixture of, macroscopically homogenous but microscopically heterogeneous, two non-miscible liquid substances.
The involved two liquid substances are called phases. One phase is continuous; the other discontinuous internal phase is dispersed in the first phase as droplets.
Foam is very similar to emulsion: the gas (often air) is dispersed as many bubbles (it is referred to as a “dispersed phase” or “internal phase”), while the aqueous liquid is fully continuous (it is referred to as a “continuous phase”).
Some of these compositions consist in immiscible dispersed systems in which the internal phase, also called dispersed phase, has a volume of greater than about 50 percent of the total volume of the composition.
Elevated internal phase emulsions conventionally consist in the so-called “medium internal phase” or “high internal phase” emulsions, also referred to as emulsions of the “MIPE” (Medium Internal Phase Emulsions) or “HIPE” (High Internal Phase Emulsions) type, respectively.
High internal phase emulsions or HIPE consist in liquid/liquid immiscible dispersed systems in which the internal phase has a volume greater than about 74%-75% of the total volume of the emulsion, i.e. a volume greater than what is geometrically possible for the compact packing of monodispersed spheres.
In turn, the medium internal phase emulsions or MIPE consist in liquid/liquid immiscible dispersed systems in which the internal phase has a volume ranging between about 50% and 74%-75% of the total volume of the emulsion.
The production of emulsions of the elevated internal phase water-in-oil type (of the MIPE or HIPE type), and their use for the manufacture of polymer foams, is for example described in the PCT application n° WO-2010/058148.
In this PCT application n° WO-2010/058148, the high internal phase emulsion is stabilized by cellulose or chitin-derived particles which, for that, are surface functionalized by hydrophobization.
However, the use of such transformed particles is likely to cause security concerns, especially for food applications, with their safety issues for the consumer.
Obtaining such transformed particles requires an additional step of surface modification.
In addition, these transformed particles are not suitable for the hydrophobic constituent encapsulation because they are intended for water-in-oil type emulsions.
In view of the above, there is a need for new elevated internal phase emulsion compositions of the oil-in-water type, for various industrial applications, especially food application.
More generally, there is a need for elevated internal phase compositions, especially emulsions, that are stabilized by agents available in large quantities, biodegradable, non toxic, renewable, of low cost and of very low densities and optionally, readily adaptable by surface modification.